The present invention relates generally to a thin film magnetic head particularly for magnetic recording, and more specifically to a magnetic head having read and write elements in an improved side by side configuration.
In high speed data processing systems, magnetic recording has been employed for large memory capacity requirements. Data is read from and written onto the magnetic recordings using magnetic transducers commonly called magnetic heads which are positioned adjacent the magnetic recording medium. For a contact recording, wherein the magnetic recording medium comes in contact with the magnetic head, the pole pieces are generally made of a magnetic ferrite material because of its wearing characteristics. The magnetic ferrite pole pieces, while having good wearing characteristics for the contact recording particularly with magnetic tape, however, lack the efficiency to record on high coercivity recording medium in the higher data density requirements for present day data recording. Magnetic heads having thin film pole pieces were developed to increase the saturation moment of the pole pieces and to increase the operating efficiency of the transducers, especially in the write or data recording procedure.
Thin film pole pieces, however, while providing the required efficiency to write the higher data density requirements, could not withstand the abrasion of the magnetic recording medium, especially in the contact recording situation. A first order requirement for high density recording is the minimizing of spacing between the surface of the media and the functional recording gap between the pole pieces. With the soft magnetic material thin film poletips of nickel-iron, for instance, the functional recording gap and the poletips are susceptible to wear by the media. Increasing the spacing between the recording gap and the media deteriorates the recording performance.
The write saturation performance characteristics of an interleaved, bi-directional, magnetic head operating in ferrite-trailing mode are not as good as those during operation in poletip-trailing mode. The mode of operation depends on the direction of tape travel: during ferrite-trailing mode, the tape travels across the gap towards the deposited poletip; in poletip-trailing mode, the tape travels towards the ferrite poletip. Regardless of write mode, a head experiences amplitude loss at high write currents. However, because of the lower saturation moment of the ferrite poletip compared to that of the deposited poletip, the amplitude loss is significantly more severe in ferrite-trailing mode. The problem thus presented is how to better balance the saturation moments of the poletips.
U.S. Pat. No. 5,296,993 describes a magnetic head with magnetic substrate and an enhanced poletip thereon. Specifically, an interleaved bi-directional magnetic tape head for contact recording can have a poletip enhanced by providing a thin film of a soft magnetic material deposited onto a magnetic ferrite substrate. The second pole piece is a thin film of the soft magnetic material. A closure block of a non-magnetic ceramic encloses the layers together with leveling insulation layers and a deposited activating conductor turns. The stripe poletip deposited onto the magnetic ferrite extends for a distance just short of the first conductor turn and provides a balancing of the saturation moment of the pole pieces and provides for better recording capability, especially when operating in a trailing magnetic ferrite mode.
While this patent is fine for its intended uses, it, like many references dealing with interleaved magnetic heads, has reader, servo, and writer contact pad areas at different levels, which complicates contacting procedures.
What is needed is a simplified contacting process that retains most, if not all, of the advantages of the prior art devices.
In accordance with the present invention, an interleaved bi-directional magnetic tape head is provided in which the read element, write element, and servo element are formed on a common substrate. Each element has a contact pad area electrically associated therewith, with each contact pad area located in a plane common to all contact pad areas. That is, the contact pad areas are planarized to each other.
As a result of such planarization, two gold conduction layers, required in the prior art, are reduced to one layer. Further, the total number of mask layers is reduced by two. Concomitantly, there is a reduction in the amount of process time. Additionally, the unit cell size is reduced by one-third of its original size.